1. Field of the Invention
This invention relates to a vinylidene fluoridetrifluoromethylethylene copolymer.
2. Description of the Prior Art
Polyvinylidene fluoride has excellent weathering resistance, corrosion resistance, electrical characteristics, processability, etc., and therefore has been used in a diversity of uses. However, since polyvinylidene fluoride has great crystallinity, great residual stress may take place by processing, cracks due to the stress are liable to be formed with lapse of time. Since it has poor flexibility, impact resistance and cold resistance are also inferior as compared with other fluorine resins.
For example, polyvinylidene film is used as lining material for chemical apparatus by virtue of its good corrosion resistance. However, when the film is subjected to stress where it is bent, for instance, at edges, it is liable to crack. Once cracks are formed, chemicals may penetrate the film and cause corrosion of the chemical apparatus.
Accordingly, as those which overcome the drawbacks of the polyvinylidene fluoride, there have been known copolymers of vinylidene fluoride with various fluorinated olefins such as tetrafluoroethylene, hexafluoropropylene, vinyl fluoride and the like.
However, no copolymer of vinylidene fluoride and trifluoromethylethylene has been known in the prior art, and also it has not been known that this copolymer has excellent flexibility.